Thiazine dyestuff and process of



Patented Feb. 2, 1937 UNITED STATES PATENT OFFICE THIAZINE DYESTUFF ANDPROCESS OF PREPARING IT Walther Hoflmann, Frankfort-on-the-Main- Hochst,Germany, assignor to General Aniline Works, Inc., New York, N. Y., acorporation of Delaware No Drawing. Application June 28, 1935, SerialNo. 28,977. In Germany July 19, 1934.

2 Claims. (Cl. 2602'7) The present invention relates to a thiazine isrun into the mixture at about 15 C. in the dyestuff which is free fromzinc chloride and course of 15 minutes, whereupon the temperature to aprocess of preparing it, particularly to a rises to about 22 C. Thewhole is stirred for thiazine dyestuff which may be obtained bycomhalf-an-hour; a solution of 39.5 parts of sodium 5 bining in knownmanner para-amino-di nethylbichromate in 115 parts of water is run inwithin 5 aniline-thiosulfonic acid with mono-methyl-or- 5 minutes andthe whole is furthermore stirred tho-toluidine in the absence of zincchloride, isofor about three-quarters of an hour. 7 parts of lating inthe absence of zinc chloride the dyecopper sulfate are then added andthe whole is stuff base which is nearly insoluble in water and heated to90 C. within 15 to 20 minutes. The

10 transforming the dyestuff base by means of an dyestuff is formed atabout 85 C., the mass as- 10 acid into the dyestuff salt. The dyestufithus suming a deep blue coloration. The temperature obtained isdistinguished by its high solubility in of 90 C. is maintained for sometime and the cold water, which is not attained, not even apchromiumsludge is then separated from the hot proximately, by any of the knownthiazine dyesolution. The dyestufi solution thus obtained is stufis.Since a solution of the new dyestuif does cooled to 40 C. and mixed with38 parts of 15 not form any deposit even on standing for a caustic sodasolution of 40B. The dyestufi base prolonged time, it is very suitablefor producing which is very sparingly soluble in water precipihectographinks. The new dyestuff surpasses the tates. It is filtered and washedfree from caustic known representatives of its series, also by its sodawith the aid of water. The red-brown dyecapability of being copied. Inparticular it gives stuff base is then made into a paste with a small 20at the beginning of the copying operation copies quantity of water.About 38 parts of hydrowhich are much more intense in colour than ischloric acid of 20 B. are added to the paste generally the case; whichis very desirable in until its reaction is weakly acid. A deep darkpractice. blue solution is obtained which is evaporated to 5 Thistechnical eflect, depending upon the exdryness, the dyestuff separatingin the form of a traordinarily high solubility of the dyestufi in coldgreen mass which may easily be powdered. The water, could not beforeseen, as, for instance, the hydrochloride thus obtained isdistinguished by isomeride of the new dyestuff, the known thiazine, avery good solubility in cold water. The coloring free from zincchloride, obtained from parapower of the dyestuff is about 25 per centgreater amino-dimethylaniline-thiosulfonic acid and dithan that of theisomeric dyestuff, free from zinc 3o methylaniline, is comparativelysparingly soluble chloride, obtained from para-amino-dimethylin coldwater. aniline-thiosulfonic acid and dimethylaniline.

The new dyestuff has, presumably, the follow- I claim: ingconstitution: 1. The dyestuff of the following constitution: 35

oneii ggoiracm /S\ N CH; IV \CH3 40 and is capable of forming a doublesalt with its 2, Process of preparng a thiazine dyestufi by acidhydrochloride. oxidizing in present of water para-amino-di- Thefollowing example serves to illustrate the methylaniline-thiosulfonicacid with monoinvention, but it is not intended to limit ittheremethyl-ortho-toluidine to the indamine-thio- 4 0; the p s are by esulfonic acid, further oxidizing it in the absence 4 parts ofpara-amino-dimethylaniline thioof zinc chloride to the thiazinedyestufi, separatsulfonic acid are suspended in 3500 parts of waing inthe absence of zinc chloride the dyestuff t r- A s l of 49 p s of -mthylin the form of its base which is nearly insoluble ortho-toluidine inparts of sulfuric acid of i water and transforming the dyestufl' baseinto 50 20 per cent. strength is added. A solution of '79 ithydrochloride. 50

parts of sodium bichromate in 230 parts of water WALTI-IER HOFFMANN.

